Typically, positioning signals received from positioning systems are presumed accurate. In addition, real-time kinematic (RTK) corrections from an external source (e.g., a base station) are used to further fine tune the position of a moving machine. Occasionally, an error in a solution obtained from a satellite system communicating with the positioning system, and/or the RTK corrections, cause a temporary jump in the position solution provided by receivers of the positioning system. This can be caused by various degradations such as signal multi-path effects or other disruptions to the signal received at the positioning system from the satellites. Short or long duration position errors may have a large impact in automation and autonomy applications.
Conventional positioning systems may typically only detect single discrete jumps. If the position jump lingers, then it would cause an error in the position output. Such conventional systems may look at signals from the individual satellites to determine when incorrect or erroneous positioning signals are being calculated or being received at a receiver.
U.S. Pat. No. 7,349,802 ('802 patent), entitled “APPARATUS AND METHOD FOR DETECTING VEHICLE LOCATION IN NAVIGATION SYSTEM,” purports to address the problem of reducing continuously accumulated errors in determining an estimated vehicle location that becomes incorrect with time. The '802 patent discusses an apparatus for detecting a vehicle location in a navigation system, where a Global Positioning System (GPS) receiver receives a navigation message transmitted by a GPS satellite, a map data storage unit stores in advance digital map data therein, and a sensor unit detects a travel angle difference and a traveled distance of a vehicle and lateral and longitudinal inclinations of a road on which the vehicle travels. A control unit of the apparatus compares the value of Dilution of Precision (DOP) of the navigation message received by the GPS receiver with a predetermined threshold. If the value of DOP is less than a predetermined threshold, the control unit sets reference vehicle location information from vehicle location information detected using the navigation message. If the value of DOP is equal to or greater than the predetermined threshold, the control unit determines the reference vehicle location information by storing vehicle location information map-matched to the digital map data when the just previous value of DOP was less than the predetermined threshold, by accumulating detection signals from the sensor unit, and by using the stored vehicle location information and the accumulated detection signals from the sensor unit. The control unit estimates the vehicle location using the determined reference vehicle location information and the detection signals from the sensor unit, map-matches the estimated vehicle location to the digital map data stored in the map data storage unit, and outputs the map-matched results to display the map-matched digital map data and vehicle location on a screen of a display unit.
However, the discussion in the '802 patent does not address what happens when the satellite signal is not available, or when there is an error in the positioning system data with multiple jumps, or even when to decide whether or not an error in the satellite data has occurred. Accordingly, there is a need for accurate detection and mitigation of positioning errors.